Related Articles

Fire blight is a plant disease that affects a variety of trees, including apple and pear, among others. Potentially devastating and difficult to control, fire blight is a bacterial infection that can destroy limbs and entire trees if left unchecked. Though several management strategies are available, selecting resistant apple cultivars is the most effective way to prevent fire blight.

Symptoms

The first symptoms of fire blight in apple trees are cankers -- areas of dead bark -- that appear in springtime on branches, twigs and trunks. The cankers usually ooze a gooey, tan-colored liquid. Fire blight also causes flowers to wilt as they appear. As the infection progresses, the trees' leaves, bark and fruit can take on a blackened appearance, as though scorched by fire, which gives the infection its name.

Causes

Fire blight is caused by the bacterium Erwinia amylovora. The disease overwinters in cankers on infected wood, and begins to spread with the arrival of warm, moist weather in spring. The infection is spread by splashing rain and insects to nearby trees or from one part of a tree to another. Human interaction can transfer the disease between trees as well. Tender new growth is most susceptible to infection, and the bacteria can also enter trees through damaged tissue.

Management

Heavy pruning during warm, wet weather can promote this disease and should be avoided. Planting apple trees far enough apart to allow good air circulation makes them less susceptible. If fire blight appears, you should remove diseased wood. Summer and winter are the best times to do this, since the bacteria does not actively spread during these seasons. All infected wood must be removed, because the infection can spread again if only a single canker is left behind. Chemical control options are often ineffective, but copper compounds are sometimes used.

Resistance

The best way to prevent fire blight is to plant apple cultivars with a high resistance to the disease. Some of the most resistant cultivars include Blairmont, Crimson Beauty, Golden Delicious, Priscilla, Spencer, Spigold and Wellington. Highly susceptible cultivars, such as Barry, Idared, Lodi, Pink Pearl and Wolf River should be avoided if you live in an area where fire blight is prevalent.

About the Author

Richard Corrigan has been a full-time professional writer since 2010. His areas of expertise include travel, sports and recreation, gardening, landscaping and the outdoors. He earned a Bachelor of Arts in English from SUNY Geneseo in 2009.